Superregenerative receiver



Dec. 4,1934. w. VAN B ROBERTS v 1,982,694 SUPERREGENERATVIVE RECEIVEROriginal Filed March 30, 1929 WALTER VAN mosms Patented Dec. 4, 19341,982,694 I SUPERREGENERATIVE RECEIVER Walter van B. Roberts, Princeton,N. J., assignor to Radio Corporation of America, a corporation ofDelaware Application March 30, 1929, Serial No. 351,411 Renewed June 22,1931 t 1 35 Claims (c1.250-2'0) The present invention relates toregenerative understood by reference to the following descripsystems,and, more particularly, to a novel tion taken in connection with thedrawing in method of, and means for, producing super-rewhich I haveindicated diagrammatically one cir-' generation in a receiving circuit.cuit organization whereby my invention may be 5 In the well known typeof super-regenerative carried into effect. I 60 receiving systems thereexists a defect whichhas The illustrated circuit shows a. source ofsuperhandicapped their wide-spread use. It is known audible frequencycurrent F coupled to a-circuit that one of the disadvantages of thesuper-re- L, C tuned to the frequency F. The circuit L, C is generativereceiving circuit is the fact that when connected to a pair of triodes1, 2, of similar charradio frequency feed back is made strong theacteristics, each of which triodes hasinserted in 65 interruptingsuper-audible frequency does not its plate circuit a feedback coil shownby T and Tr, fulfill'its function completely enough. i That is torespectively, magnetically coupled to a coil L1. say, before the fulleffect of the super audible The grid of each triode is biased, as shown,both frequency damping is achieved, the regenerative grids being, forexample, equally biased throu h amplifier tube begins again to build upthe incomhigh resistance R which is preferably connected ipletely qu n dlat ns, pr ducin more to the middle of coil L, and through the common orless sustained radio frequency oscillations. parallel resonant circuitL1, C1 to a point on the Now,'I have discovered a method of positivelyfilament circuits. of the triodes 1, 2. stopping, during the dampingperiod, Oscillations The feedback coil T, connected in the plate-cirof ay s n th at may be built up du ing the cuit of triode 1, is connected tothe reversed feedamplifying p e arrangement devised by back coil Tr, thelatter coil being connected in me to embody this method utilizes afeedback, the plate circuit of triode 2. A source of plate, whichI terma reverse feedback, i opposition to potential, and a utilization means,such as the amplifying feedback, a d t e ev s d feed? phones, are commonto the output circuits of the 25; back action is periodicallysubstituted for the t i 1 2 A usual by-pass condenser is regenerativefeed back by the interrupting superh t d across th phones audiblefrequency current. The circuit L, C is fixedly tuned to the super-Acoord y. t is one of the main objects of audible frequency F. It willbeseen at once that my present invention to provide a method of, and iththe arrangement shown, when the grid of In producing Supe in a triode lis less negative than normal, the grid ceiving circuit-which comprisesutilizing areverse. of triode 2 l be more negative t normaL feedbackaction o rapid quenching of radio While-the grid'of triode2 is verynegative, the fr qu y oscillations dur n thedampineperied, triode 2 isineffective. But, it should be noted without introduc pp e da p into thethat the grid of triode 1 is only slightly negative,

35 oscillation circuit during the regeneratively and, due to the actionof feedback coil '1' and coil amplifying, or building up, period. L1,triode 1 builds up oscillations in the radio Another important object ofthe invention is to frequency it, the amplitude at a given'time providea receiving circuit of the super-regendepending upon th signal input ierative type in which a pair of triodes of similar Due t th reversing tiof th superhudl 40 characteristics is utilized, one Of the triodesfuncible frequency energy F, the grid of triode 1 next tioning as the ap fi and having a feed-back becomes very negative, while the grid oftriode 2 coil associated therewith, the other triode having becomes onlyslightly negative. This results in a second feed-back coil associatedtherewith and the reverse feedb k coil T building d or fu ct o g as areverse feed-back means, positively quenching the oscillations, thustaking 45 entire op a of t amplifying action being the place of ohmicresistance in quenching oscilinitiated y an interrupting supcr-audiblevi lations at super-audible frequency. It should. q y i such a mannerthat the reverse feedalso be noted that the method described herebackmea s begins to quench oscillations in the in allows the use of anothertuned circuit loosely amplifier triode prior to the instant whenoscillacoupled t t radio frequency circuit, Since th '50 #0 5 of eamplifier Would otherwise attain an reversed feedback may be increasedto suchexundesirable amplitude The novel features which tent as to wipeout residual oscillations in this Ibelieve to be characteristic of myinvention are extra circuit a1s0 set forth particularity in t e pp c claIn other words, the arrangementl have. shownh Invention itself, however,t o 1175 makes it possible to connect a pre-selector cir- 55 i e i andmethod f operation will b t be cuit as, for instance, a band-passcircuit, or a 11.0

tuned stage of radio frequency amplification, or an untuned stage ofradio frequency amplification, or all three, or any two between theantenna and the radio frequency circuit L1, C1.

The reactions and interactions taking place in the circuit may beillustrated by the following mathematical expressions, the latterserving the purpose of laying down rules of design, whereby anyone,skilled in the art, may construct the circuit of this invention. It canbe shown that the feedback from the tickler 'I is proportional to,

cn-E sin Ft The feedback from the coil Tr is proportional to,

(-a2E sin Ft) The total feedback, therefore, is equal to,

(a1-(l2) -2E Sin F15 It is merely necessary to keep the constant term(ii-a2 of a negative value, or of suficiently small positive value thatit is not enough to completely wipe out the ohmic resistance of theradio frequency circuit, in order to produce the action describedheretofore, it being understood that,

a1=the amount of negative resistance fed back to the input circuit inthe absence of E,

az=the amount of positive resistance ffed back to the input circuit inthe absence of E,

E=the maximum extra resistance fed back when the peak voltage offrequency F is applied to the grids. n

It is to be observed that a further advantage of this circuit resides inthe fact that the voltage of frequency F being differentially applied tothe grids, the current through the phones does not vary at frequency Fto nearly so great an extent as in the ordinary single tubesuper-regenerative arrangement, where there must be large currents ofinterruption frequency through the phones, unless elaborate filteringarrangements are used to separate such currents from the desiredsignals. I

In the drawing it is to be understood that the source of energy to beamplified is coupled or otherwise connected across the coil L1.

While I have indicated and described only one system for carrying myinvention into effect, it will be apparent to one skilled in. the artthat my invention is by no means limited to the particular organizationshown and described, but that many modifications in the circuitarrangement, as well as in the apparatus employedjmay be madewithoutdeparting from the scope of my invention as set forth in the appendedclaims.

What I claim is: I

, i. A super-regenerative receiving circuitcomprising a pair of triodesof similar characteristics having grid and plate circuits, a tunedcircuit common to the grid circuits of both triodes, one of said triodeshaving its plate circuit coupled to the tuned circuit in its gridcircuit, the other triode having its plate circuit reversely coupled tosaid tuned circuit, and'a source of interrupting current coupled to thegrid circuits of said triodes said current being of a super-audible fre}nant circuit in a reverse manner, a source of interrupting currentcoupled to said input circuits, the current being of a super-audiblefrequency, the resonant circuit being tuned to said frequency.

3. A method of operating a super-regenerative receiver provided with anamplifier employing a feedback action and a reverse feedback actionwhich consists in subjecting signal energy to the amplifier employingthe feedback action, subjectingthe signal energy to the reverse feedbackaction, in opposition to the amplifying feedback,

and periodically rendering the reverse feedback operative therebypositively stopping oscillations of any strength that may be built upduring the amplifying period.

4. A method of operating a super-regenerative "receiver which consistsin subjecting signal enreverse feedback operative thereby positivelystopping oscillations of any. strength that may b built up during theamplifying period.

5. A method .ofoperating a super-regenerative receiver which consists infeeding thesignal energy to the receiver and. subjecting signal energyto an amplifying feedback action, supplying an interrupting current ofsuper-audible frequency to the receiver, and utilizinglthe interruptingcurrent to periodically impress a reverse feedback action, in oppositionto the amplifying feedback, for the amplifying feedback. 6. Inasuper-regenerative amplifier provided with a signal input circuit andan output circuit, themethod of maintaining a definite relationshipbetween the amountcf damping action during the damping period and theamount of undamping action during the building up period which includesthe steps of applying signal energy to the amplifier, feeding backenergy from the amplifier output to the input thereof in regenerativephase, feeding back energy to the amplifier input in degenerative phaseand periodically and harmonically varying the strength of both feedbacksin inverse sense so that the equivalent-single resultant feedback isalternatively regenerative and degenerative in phase.

'7. The method of operating a super-regenerative receiver which consistsin feeding the signal energy to the receiver and subjecting signal oneergy to an amplifying feedback action, supplying an interrupting currentof super-audible frequency to the receiver. feeding back signal en ergy,in opposition to theamplifying feedback, and utilizing the interruptingcurrent to periodi cally substitute the opposing feedback for theamplifying feedback, forrapid quenching of radio frequency oscillationsduring the damping period.

8. A method of operating .a supereregenerative receiver which consistsin feeding the signal en ergy to' the receiver and subjecting signalenergy to an amplifier employing a feedback action, supplying aninterrupting current of super-audible frequency to the receiver,subjecting the signal energy to a reverse feedback action, in oppositionto the amplifying feedback, and utilizing the interrupting current toperiodically substitute the reverse feedback for the amplifying feedbackthereby positively stopping radio frequency oscillations during thedamping period.

9. In a feedback circuit, themethod of securing great amplificationwithout building up sustained oscillations which comprises periodicallyreversing the phase of the feedback.

10. The method ofiamplifyingivarying electric currents which comprisesimpressingthe varying potential of the currenttozbe amplified upon afeedback circuittand periodically reversing the phaseof the feedbackwhereby super-regenerative,

action i's'obtained." l l1. The method of amplifying varying electriccurrents which comprises impressingthe varying potential of the currenttobe amplified upon a system including feedback means andcounterfeedback means andwperiodicallyaltering the relation between theamount of feedback and the amount of counter-feedbackcf the system,whereby superregenerative actionis' obtained.

12. The methodof amplifying varying electric currents which comprisesimpressing the varying potential of the current to be amplified upon asystem including a feedback circuit and a counter-feedback circuit andperiodically" varying the relation between the amount of feedback andthe amount of counter-feedback; at some frequency a system: including afeedback circuit and also" upon a counter-feedback circuit andperiodically varying both the amount of feedback and the amount ofcounter-feedback whereby super-regenerative action is obtained.

15. The method of amplifying varying electric currentsiwhich comprisesimpressing the varying potential of the current itosbe'amplified upon asystem including feed-back means. adjusted near the'pointnof oscillationand'a counter-feedback means and periodically "varying the. relativeamountszof feedback and 'of V counter-feedback whereby thelnet amount:of -feedback varies periodically about said value which is near thepoint of oscillation. 1'

a 16; The method of amplifying varying electric currents which comprisesimpressing the varying potential. ofthecurrent tozbe amplified upon asystem including a feedback circuivand upon a counter-feedback circuitand periodically varying 'both thelamount of thefeedbackan'd theamount'of the counter-feedback'ofsaid circuits at some frequencyrelatively low as compared: to the frequency of the current to beamplified whereby super-regenerative action is obtained. 2 i

put and output circuits coupled so'as to produce a feedback system, asecond thermionic tube having input and output circuits coupled so as toproduce a counter-feedbacksystem; means for impressing said energyuponiboth said systems and meansassociated with both said systems forperiodically altering thesrelationzbetween the amount of feedback andtheamount of counter-i as to produce a feedback system, a second thermioffeedback and the amount a offoscillation and means for periodicallyvarying 1 17, Apparatus for amplifying varyingielectricl energycomprising a' thermionic tube having in onic tube having input andoutput circuits coupled was to produce a counter-feedback system, saidtwo systems having common input and output circuits and means forperiodically varying the relation between the amount of feedback and theamount of counter-feedback at some frequency relatively low compared tothe frequency of the current to be amplified; i r 19. Apparatus foramplifying varying electric currents comprising-a thermionic tubehavinginput and outputcircuits coupled so as to form a. feedbackcircuit, a second thermionic tube having input and output circuitscoupled so as to form a counter-feedback circuit, said two :circuitshaving common input and output circuits, means for impressing thepotential of saidcurrents-on said common input circuit thereby causingsaid feedback circuit to. generatev oscillations and means forperiodically varying theamount of counter-feedback in saidcounter-feedback circuit thereby stopping the generation of oscillationsin said feedback "circuit whereby 'superregenerative actionis obtained.i i

20. Apparatus for amplifying varying electric currents comprising athermionic tube having input and output circuits coupled so as to formfeed-back circuit, a second thermionic tube having input and .outputcircuits coupled so as toform a counter-feedback circuit, saidtwocircuits having common input and output circuits, means, for impressingthe potential of said currents upon the inputs of both said circuits andmeans differentially applied to the inputs of said feedback andcounter-feedback circuits for"periodically varying the amountofcounter-feedback in said counter-feedback a circuit, said circuits beingadapted to generate oscillations in accordancewith the action of thefeedback circuit and to prevent the generation of oscillations inaccordance with theaction of the counter-feedback circuit'wherebysuper-regenerative action is obtained. 5

-21. Apparatus for amplifying varying electric currents comprisinga'thermionic tube having input and output circuits coupled-so as toforma a feedback system, a second thermionic tube havingcoupled inputand output circuits soas to formra counter-feedback system, said systemshavinglcommon input and output circuits and means for periodicallyvarying both the amount of counter-feedback ofsaid system. H

I 22. Apparatus for amplifying varying electric currents comprising, athermionic tube having input and .output'circuits coupled so as'to"forr'ni a feedback. system, a second thermionic tube having inputv andoutput circuitscoupled so as to. form a counter-feedback system, saidsystem s having common input and output circuits, said feedback systembeing adjustednear the point thewamount of feedback with "respect to theamount of counter-feedback of saidsy'stemsi x 23; Apparatus foramplifyingyaryingelectric;

currents comprising, a thermionic tubefeedback system having an inputcircuit and an output circuit, a thermionic tube counter-feedback sys"tern having an input circuit andnan output circuit,.

a portion ofieach of said two input circuits being 24. In asuper-regenerativev circuit an electron discharge tube. regenerativesystem comprising a. feedback circuit in combination with an electrondischarge tube degenerative system comprising acounter-feedback.circuit, means for adjusting said. regenerative systemnear the point of oscillation, a source of oscillations associated-withboth said systems and means controlled thereby for causing a periodic.variationin the relation between the amount of feedback in said feedbackcircuit and the amount of counter-feedback in said counter-feedbackcircuit.

25. In a super-regenerative receivermeans for amplifying varyingelectric currents comprising a feedback system and a counter-feedbacksys-- tem, said two systems having common input and output circuits,means for. periodically varying both the amount of feedback and theamount of counter-feedback of said systems at some frequency relativelylow compared to the'frequency of the current to be amp1ified, the amountof' counter-feedback being of suchan extent that it influences circuitscoupled to said system but periodically varying the total effectiveresistance of said circuit about. a mean value greater than zero andmeans for making the maximum posi tive value of effective resistance of.said. circuit.

greater thanthe natural ohmic resistance of the oscillatory circuit.

. w .1 2'7. Inv apparatus for amplifying varying elec-* tric currents, aresonant circuit, means for vary- 5 ing the net eifectiveresistance ofsaid resonant circuit periodically about a mean positive value atafrequency low comparedto the natural frequency of said resonant circuitand meansfon making, the maximum attained positive value of -.efiecti-veresistance greater than the natural ohmic resistance of the, resonantcircuit.

28. In apparatus for amplifying varying electric currents, anoscillatory circuit comprising re-- generative means and degenerativemeans, means,

for periodically varying the total effective resistance of said circuitabout a mean value. greater than zero and means comprising saiddegenera-.

tivemeans for making the maximumpositive value of effective resistanceof said-circuit greater.- than the naturalohmic resistance thereof;

29. In a super-regenerative circuit,;a pair of signal energy transferredfrom said source to said tuned circuit being adapted to affect boththermionic tubes in like sense, a source of super-audible frequencywaves differentially coupled to both said input. circuits, meansforcoupling the output circuit of one of said thermionic? devices to itsinput circuit in a sense to cause regenerationand means for coupling theoutput and input circuits of the other thermionic device in a senseto'cause de-generation.

30. In a super-regenerative circuit, a" pair of thermionic tubes havinginput and output circuits, the two input circuits'-"having a common.portion including a tuned circuit and the two out-- put circuits havinga common. portion including a load circuit, means for couplingasource ofSignal energy to said commontuned circuit, the signal energy transferredfrom said source-to ,saidwtuned. circuit being adapted to affect boththermionic; tubescin like sense, means for cou pling' the output circuitof one of said thermionic devices to its input. circuit in a sense tocause regeneration, means for coupling theoutput. and input circuits ofthe other thermionic. device in a sense. to causedegeneration, and meanscomprising asource. of supersonic. frequency waves foralternatelvrendering said two circuits inoperative'.

31. Ina super-regenerative receiver, a regenerative circuit including aspace discharge device, damping meansv forsaid regenerative circuitcomprising a degeneration circuit including aspace discharge device, asource of signal energycoupled tobothsaid circuits, 2. load common toboth circuits and means for rendering said circuits alternately andperiodically operative and inoperative.

32.'.,The method. of signal wave amplification which comprises buildingup oscillations to an intensity many times greater but proportional tothe intensity ofv the signal wave to be amplified and periodicallyreducing to a substantial degree the intensity of the builtuposcillations at a super-audible'rate,thebuilding-up rate of theoscillations being substantially lower than the reduction rate.

33. In a super-regenerativecircuit comprising at least oneelectronictube provided with an in-' put circuit'and an output circuit, asource ofinterruption frequency voltage coupled to one of saidcircuits,.an audiooutput circuit connected to the output of said device and means foropposingv in said audio. output circuit the current of interruptionfrequency fed. thereto from said electronictube.

3.4. In a super-regenerative circuit including at least one electronicdischarge tube provided with input and output circuits, .9. source ofinterruption frequency voltage coupled to said input circuit, an audio.output: circuit connected to. the output circuit of said device, andmeans for opposing in said audio output circuit the current ofinterruption frequency fed thereto through the electronic tube, saidmeans comprising a circuit arrangement including said audio outputcircuit and adapted to cause a current to flow through the audio outputcircuit of phase and magnitude -.to substantially neutralize the effect.of said. current of interruption frequency flowing through the;audio-output circuit.

35. In a super-regenerative circuit including at least one electrondischarge tube provided with an input circuit and an output circuit, anaudio output circuit connected to the output circuit of said tube,.asource of. interruptionfrequency voltage connectedto one of saidelectron discharge tube circuits so. as to transfer interruptionfrequency energy thereto whereby energy of said interrupting frequencyis present in the output circuit of said tube, means for opposing insaid audio output circuit the energy of interruption frequency fedtheretofrom the tube output circuit comprising a circuit arrangementincluding said audio outpute'circuit and adapted. to cause a current toflow through the audio output circuit of. such phase and magnitude. asto substan tially neutralize the effect of the energy of interruptionfrequency transferred. to the audio output circuit from the tube. outputcircuit.

WALTER VAN B. ROBERTS.

